The present invention relates to screw fasteners. More particularly, the invention relates to wocd screws which have uniquely formed interrupted threads and inherent resiliency so as to provide enhanced resistance to loosening.
Conventional screws used in fastening to boards of wood, chip-board, and the like are provided with continuous threads which are screwed into the board with such force as to make a thread in the board to achieve a degree of fastening. Such screws are rigid and, even though considerable force must be utilized in driving the screw to part the material of the board, can loosen because of limited resistance to reverse motion of the screw thread along the mating thread in the board. Thus, known wood screws are likely to become loose in time unless spring washers, or other devices are placed under the head of the screw. It has also been a practice to use glues in conjunction with screws in order to obtain more reliable and secure joints. However, glues harden and crystallize in time, allowing loosening, and glues tend to bleed into the wood with attendant discoloration. Furthermore, both the use of spring washers and the application of glue involve added cost and inconvenience.
There is need, therefore, for a wood screw which, after being driven in a mating part will inherently provide enhanced resistance to loosening.